Reaction of aminosulfur trifluorides with alcohols: inversion vs. retention

Abstract

Reaction of aminosulfur trifluorides with alcohols replaces the hydroxy group with fluorine. A study with the cyclic secondary alcohols trans-2-bromoindan-1-ol (3), trans-2-methylcyclopentanol (7), cis-2-methylcyclopentanol (8), trans-[2-²H₁]cyclopentanol (9), cis-[2-²H₁]cyclopentanol (10) and trans-2-fluorocyclopentanol (11) gave primarily inversion of configuration via an S_N1-like pathway. The product stereochemistry and alkene formation in the reaction of aminosulfur trifluorides with cyclopentanols was similar to the products of solvolysis of cyclopentyl tosylates in methanol. The stereochemistry of the fluoro products was confirmed by independent synthesis or assigned by ¹H and ¹⁹F NMR spectral data except for the deuteriated products 14 and 15 whose stereochemistry was assigned by their ²H NMR data.